Apparatus and method for controlling piston cooling oil jet

ABSTRACT

An apparatus for controlling a piston cooling oil jet may include a main gallery supplied with oil, an oil jet gallery defining an oil injection path such that the oil through the main gallery is introduced and is sprayed to a lower portion of a piston, an oil jet valve opening the oil injection path such that the oil supplied to the main gallery is introduced into the oil jet gallery, and a controller electrically connected to the oil jet valve, and determining a target oil pressure through a first factor value corresponding to an RPM and an engine load, a second factor value determined by a predetermined target oil pressure curve, and a third factor value corresponding to an RPM and an oil temperature in the main gallery to control an opening degree of the oil jet valve using the target oil pressure.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to Korean Patent Application No.10-2016-0063186 filed on May 24, 2016, the entire contents of which isincorporated herein for all purposes by this reference.

BACKGROUND Field of the Invention

The present invention relates to an apparatus and method for controllinga piston cooling oil jet. More particularly, it relates to an apparatusand method for controlling a piston cooling oil jet, capable ofimproving performance of a piston and fuel efficiency.

Description of Related Art

In general, an internal combustion engine compresses and explodes fueland air introduced into a combustion chamber so that pistons reciprocateup and down, and converts the reciprocation of the pistons intorotational motion using a crank mechanism so as to obtain rotary power.

The internal combustion engine may often rotate at a high speed due tothe occurrence of friction between components and a large load appliedthereto during operation.

The force applied to such a friction portion may be lost due toresistance, together with the force generated in the expansion stroke ofthe cylinder added thereto. The friction between components causes thequick wear and short life of the associated components. This causes theperformance of the internal combustion engine to deteriorate.

Currently, a piston used in an internal combustion engine is mainly madeof an aluminum alloy having light weight and high heat transmissibility.However, an aluminum alloy has a disadvantage in that tensile strengthand hardness are reduced at high temperature.

Hence, the head portion of the piston is subjected to high heat as amixture is combusted in an upper combustion chamber, which may lead toproblems relating to a reduction in strength, a heat strain, aluminumadhesion, excess abrasion of rings, etc. Moreover, the higher thetemperature of the piston, the faster the degradation of oil, which maycause a carbon deposit to be excessively formed.

Therefore, in order to prevent the engine from being damaged due tothese problems, the power of the engine may be adjusted or the passageof coolant may be changed such that the temperature of the piston ismaintained below a certain level, but the effect thereof is not great.

Accordingly, the related art adopts a method of cooling a piston byspraying oil from the lower portion of the piston using an oil jet inorder to effectively reduce the temperature of the piston. That is, whenan oil pump pumps oil and transfers it to a main gallery, the oil jetsprays the oil to the oil jet gallery of the piston, thereby cooling thehead portion of the piston.

In the method of cooling the piston, when the engine is started and apressure is generated in oil, the oil is sprayed, regardless of RPM(revolutions per minute) and a load condition, and therefore the oil jetis always operated. Accordingly, a capacity of the oil pump is increasedand the increased capacity acts as the load of the engine, and thus fuelefficiency may deteriorate.

The information disclosed in this Background of the Invention section isonly for enhancement of understanding of the general background of theinvention and should not be taken as an acknowledgement or any form ofsuggestion that this information forms the prior art already known to aperson skilled in the art.

BRIEF SUMMARY

Various aspects of the present invention are directed to providing anapparatus and method for controlling a piston cooling oil jet, capableof improving performance of a piston and fuel efficiency by determininga target oil pressure through a power compensation map, a target oilpressure curve, and a temperature compensation map, which are set usingan RPM, an engine load, and an oil temperature, and by comparing andcontrolling the determined target oil pressure and a current oilpressure to determine an opening degree of an oil jet valve for coolingthe piston.

In an exemplary embodiment, an apparatus for controlling a pistoncooling oil jet includes a main gallery supplied with oil, an oil jetgallery defining an oil injection path such that the oil passing throughthe main gallery is introduced thereinto and is sprayed to a lowerportion of a piston, an oil jet valve opening the oil injection pathsuch that the oil supplied to the main gallery is introduced into theoil jet gallery, and a controller electrically connected to the oil jetvalve, the controller determining a target oil pressure through a firstfactor value corresponding to an RPM and an engine load, a second factorvalue determined by a predetermined target oil pressure curve, and athird factor value corresponding to an RPM and an oil temperature in themain gallery, to control an opening degree of the oil jet valve usingthe target oil pressure.

The controller may include a power compensation map setting deviceallowing the first factor value to be set, a target oil pressure curvesetting device allowing the second factor value to be set, a temperaturecompensation map setting device allowing the third factor value to beset, and a determination device configured to determine the target oilpressure by adding a first pressure value, which is obtained bymultiplying the first and second factor values in the same condition ofRPM, to a second pressure value, which is obtained by a differencebetween the second and third factor values.

The power compensation map setting device may allow the first factorvalue to be set from an RPM detected by an RPM detection device and anengine load in the RPM.

The target oil pressure curve setting device may allow the second factorvalue corresponding to an RPM detected by an RPM detection device to beset from the predetermined target oil pressure curve.

The temperature compensation map setting device may allow the thirdfactor value to be set from an RPM detected by an RPM detection deviceand an oil temperature in the main gallery measured in the RPM.

The oil jet valve may be an electronic solenoid proportional controlvalve.

The controller may compare the target oil pressure with a current oilpressure in the main gallery and an oil pressure in the oil jet gallerythrough Proportional Integral (PI) control, and control the openingdegree of the oil jet valve.

In another exemplary embodiment, a method of controlling a pistoncooling oil jet includes setting a first factor value, a second factorvalue, and a third factor value using an RPM, an engine load, and an oiltemperature in a main gallery, and determining a first pressure value bymultiplying the first and second factor values in the same condition ofRPM, determining a second pressure value by a difference between thesecond and third factor values in the same condition of RPM, anddetermining a target oil pressure by adding the first pressure value tothe second pressure value.

The method may further include controlling an opening degree of an oiljet valve by comparing the target oil pressure with a current oilpressure in the main gallery and an oil pressure in an oil jet gallery.

In the setting of a first factor value, a second factor value, and athird factor value, the first factor value may be set from an RPMdetected by an RPM detection device and an engine load in the RPM.

In the setting of a first factor value, a second factor value, and athird factor value, the second factor value corresponding to an RPMdetected by an RPM detection device may be set from a predeterminedtarget oil pressure curve.

In the setting of a first factor value, a second factor value, and athird factor value, the third factor value may be set from an RPMdetected by an RPM detection device and an oil temperature in the maingallery measured in the RPM.

Other aspects and exemplary embodiments of the invention are discussedinfra.

It is understood that the term “vehicle” or “vehicular” or other similarterm as used herein is inclusive of motor vehicles in general such aspassenger automobiles including sports utility vehicles (SUV), buses,trucks, various commercial vehicles, watercraft including a variety ofboats and ships, aircraft, and the like, and includes hybrid vehicles,electric vehicles, plug-in hybrid electric vehicles, hydrogen-poweredvehicles and other alternative fuel vehicles (e.g. fuels derived fromresources other than petroleum). As referred to herein, a hybrid vehicleis a vehicle that has two or more sources of power, for example bothgasoline-powered and electric-powered vehicles.

The above and other features of the invention are discussed infra.

The methods and apparatuses of the present invention have other featuresand advantages which will be apparent from or are set forth in moredetail in the accompanying drawings, which are incorporated herein, andthe following Detailed Description, which together serve to explaincertain principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view schematically illustrating an apparatus for controllinga piston cooling oil jet according to an exemplary embodiment of thepresent invention;

FIG. 2 is a view illustrating a controller of the apparatus forcontrolling a piston cooling oil jet according to the exemplaryembodiment of the present invention;

FIG. 3 is a graph illustrating a target oil pressure curve for theapparatus for controlling a piston cooling oil jet according to theexemplary embodiment of the present invention;

FIG. 4 is a flowchart illustrating a method of controlling a pistoncooling oil jet according to another exemplary embodiment of the presentinvention;

FIG. 5 is a block diagram illustrating a control logic of the method ofcontrolling a piston cooling oil jet according to the exemplaryembodiment of the present invention; and

FIG. 6 is an exemplary table for determination of a target oil pressurein the method of controlling a piston cooling oil jet according to theexemplary embodiment of the present invention.

It should be understood that the appended drawings are not necessarilyto scale, presenting a somewhat simplified representation of variousexemplary features illustrative of the basic principles of theinvention. The specific design features of the present invention asdisclosed herein, including, for example, specific dimensions,orientations, locations, and shapes will be determined in part by theparticular intended application and use environment.

In the figures, reference numbers refer to the same or equivalent partsof the present invention throughout the several figures of the drawing.

DETAILED DESCRIPTION

Hereinafter reference will now be made in detail to various embodimentsof the present invention, examples of which are illustrated in theaccompanying drawings and described below. While the invention will bedescribed in conjunction with exemplary embodiments, it will beunderstood that present description is not intended to limit theinvention to those exemplary embodiments. On the contrary, the inventionis intended to cover not only the exemplary embodiments, but alsovarious alternatives, modifications, equivalents and other embodiments,which may be included within the spirit and scope of the invention asdefined by the appended claims. In addition, detailed descriptions offunctions and constructions well known in the art may be omitted toavoid unnecessarily obscuring the gist of the present invention.

FIG. 1 is a view schematically illustrating an apparatus for controllinga piston cooling oil jet according to an exemplary embodiment of thepresent invention. FIG. 2 is a view illustrating a controller of theapparatus for controlling a piston cooling oil jet according to theexemplary embodiment of the present invention. FIG. 3 is a graphillustrating a target oil pressure curve for the apparatus forcontrolling a piston cooling oil jet according to the exemplaryembodiment of the present invention.

As illustrated in FIG. 1, the apparatus for controlling a piston coolingoil jet includes a main gallery 100, an oil jet gallery 200, an oil jetvalve 300, and a controller 400.

First, the main gallery 100 is mounted in a cylinder block of a pistonso that oil is supplied along an inside passage of the main gallery bythe driving of an oil pump.

In addition, the oil jet gallery 200 defines an oil injection path suchthat the oil passing through the main gallery 100 is introducedthereinto and is sprayed to the lower portion of the piston.

The oil jet valve 300 opens the oil injection path such that the oilsupplied to the main gallery 100 is introduced into the oil jet gallery200 as the pressure of the oil is increased.

Here, the oil jet valve 300 is an electronic solenoid proportionalcontrol valve, and is electrically connected to the controller 400. Theopening degree of the oil jet valve 300 may be adjusted by the controlof the controller 400.

That is, a conventional oil jet valve is a mechanical control valve, theopening degree of which may not be independently adjusted and controlledby the control of a controller. For this reason, the same amount of oilis always supplied to a piston, regardless of conditions including anRPM, an engine load, and an oil temperature.

In other words, since a conventional flow rate required for cooling apiston is set on the basis of the high-load region of an engine, anexcessive surplus flow rate occurs due to the excessive injection of oilin the low-load region of the engine. This may lead to the deteriorationof performance of the piston and the deterioration of fuel efficiency.Moreover, there is a problem in that, since the same amount of oil mayalways be supplied to the piston, it is necessary to increase thecapacity of an oil pump.

The controller 400 according to the embodiment may determine a flow raterequired for a piston, using an RPM, an engine load in the RPM, and anengine temperature, and thus may effectively control the opening degreeof the oil jet valve 300. As a result, it is possible to resolve theabove problems.

The controller 400 determines a target oil pressure in the oil jetgallery 200, through a first factor value corresponding to an RPM and anengine load, a second factor value determined by a predetermined targetoil pressure curve, and a third factor value corresponding to an RPM andan oil temperature in the main gallery 100, and controls the openingdegree of the oil jet valve 300 using the determined target oilpressure.

To this end, the controller 400, which is electrically connected to theoil jet valve 300, includes a power compensation map setting device 410,a target oil pressure curve setting device 420, a temperaturecompensation map setting device 430, and a determination device 440, asillustrated in FIG. 2.

Here, the power compensation map setting device 410 allows the firstfactor value to be set from an RPM detected by an RPM detection deviceand an engine load detected in the RPM.

The target oil pressure curve setting device 420 is preset, and allowsthe second factor value corresponding to an RPM detected by the RPMdetection device to be set from a predetermined target oil pressurecurve, as illustrated in FIG. 3.

The temperature compensation map setting device 430 allows the thirdfactor value to be set from an RPM detected by the RPM detection deviceand an oil temperature in the main gallery 100 measured in the RPM.

The determination device 440 determines the first, second, and thirdfactor values in the same condition of RPM, and determines a target oilpressure by adding a first pressure value, which is obtained bymultiplying the first and second factor values, to a second pressurevalue, which is obtained by a difference between the second and thirdfactor values.

That is, the target oil pressure may be determined by the equation of“Target oil pressure=(first factor value×second factor value)+(secondfactor value−third factor value)”. The controller 400 compares andcontrols a current oil pressure in the main gallery 100 and an oilpressure in the oil jet gallery 200 through Proportional Integral (PI)control using the target oil pressure, and thus determines a flow raterequired for a piston to control the oil jet valve 300. As a result, itis possible to effectively control the opening degree of the oil jetvalve 300.

Accordingly, the apparatus for controlling a piston cooling oil jetaccording to the embodiment can control the oil jet valve 300 bydetermining the target oil pressure through the power compensation map,the target oil pressure curve, and the temperature compensation map,which are set using the RPM, the engine load, and the oil temperature inthe main gallery 100, adjusting the opening degree of the oil jet valve300 depending on the high-load region and low-load region of the engine.Therefore, it is possible to improve the performance of the piston andfuel efficiency and to simultaneously reduce the capacity of the oilpump for transferring oil to the main gallery 100.

FIG. 4 is a flowchart illustrating a method of controlling a pistoncooling oil jet according to another exemplary embodiment of the presentinvention. FIG. 5 is a block diagram illustrating a control logic of themethod of controlling a piston cooling oil jet according to theexemplary embodiment of the present invention. FIG. 6 is an exemplarytable for determination of a target oil pressure in the method ofcontrolling a piston cooling oil jet according to the exemplaryembodiment of the present invention.

The method of controlling a piston cooling oil jet and the control logicthereof will be described with reference to FIG. 4 and FIG. 5.

First, a first factor value, a second factor value, and a third factorvalue are set using an RPM, an engine load, and an oil temperature in amain gallery (S100).

Here, the first factor value is set from an RPM detected by an RPMdetection device and an engine load in the RPM. The set first factorvalue is stored as in the table of a power compensation map illustratedin FIG. 6.

The second factor value is set to be a value corresponding to an RPMdetected by the RPM detection device from a predetermined target oilpressure curve illustrated in FIG. 3. The set second factor value isstored as in the table of a target oil pressure curve illustrated inFIG. 6.

The third factor value is set from an RPM detected by the RPM detectiondevice and an oil temperature in the main gallery measured in the RPM.The set third factor value is stored as in the table of a temperaturecompensation map illustrated in FIG. 6.

When the first, second, and third factor values are set (S100), a firstpressure value is obtained by multiplying the first and second factorvalues in the same condition of RPM, a second pressure value is obtainedby a difference between the second and third factor values in the samecondition of RPM, and a target oil pressure is determined by adding thefirst pressure value to the second pressure value (S200).

Finally, an opening degree of an oil jet valve is controlled bycomparing the target oil pressure with a current oil pressure in themain gallery and an oil pressure in an oil jet gallery (S300).

Meanwhile, an example of determining a target oil pressure by comparinga first operation condition, in which the RPM is 1800 rpm, thetemperature in the main gallery is 60° C., and the engine load is 10%,with a second operation condition, in which the RPM is 1800 rpm equal tothat in the first operation condition, the temperature in the maingallery is 100° C., and the engine load is 80%, will be described withreference to FIG. 6.

First, it can be seen that the first factor value is 0.10 through thepower compensation map and the second factor value is 155 through thetarget oil pressure curve in the first operation condition.

Thus, the first pressure value is “0.10×155=15.5 kPa”.

The third factor value is confirmed to be 129 through the temperaturecompensation map, and the second pressure value is “155−129=26 kPa”.Therefore, the target oil pressure is 41.5 kPa by the equation of“Target oil pressure=first pressure value+second pressure value”indicated in the target oil pressure determination step (S200).

Meanwhile, it can be seen that the first factor value is 0.92 throughthe power compensation map and the second factor value is 155 throughthe target oil pressure curve in the second operation condition.

Thus, the first pressure value is “0.92×155=142.6 kPa”.

The third factor value is confirmed to be 155 through the temperaturecompensation map, and the second pressure value is “155−129=0 kPa”.Therefore, the target oil pressure is 142.6 kPa by the equation of“Target oil pressure=first pressure value+second pressure value”indicated in the target oil pressure determination step (S200).

According to the exemplary embodiment of the present invention, theperformance of the piston and fuel efficiency may be improved since thetarget oil pressure is determined differently depending on the first andsecond operation conditions and thus the opening degree of the oil jetvalve is controlled depending on the conditions.

In the related art, assuming that the flow rate required in a first loadcondition, in which the RPM is 1800 rpm and the engine load 100%, is 5.2L/min, and the flow rate required in a second load condition, in whichthe engine load is 10% in the same RPM, is 0.5 L/min, the flow rate,which is set by the oil jet in the RPM of 1800 rpm, has an upper limitof 7.3 L/min. Therefore, the surplus flow rate in the first loadcondition is 2.1 L/min, and the surplus flow rate in the second loadcondition is 6.8 L/min.

Accordingly, since the conventional flow rate required for cooling apiston is set on the basis of the high-load region of an engine, anexcessive surplus flow rate may occur in the low-load region of theengine. However, since the opening degree of the oil jet valve can becontrolled according to the target oil pressure in the exemplaryembodiment, it is possible to prevent the excessive flow rate of oilfrom occurring in the low-load of the engine.

The present invention has an effect of improving the performance of thepiston and fuel efficiency by determining the target oil pressurethrough the power compensation map, the target oil pressure curve, andthe temperature compensation map, which are set using an RPM, an engineload, and an oil temperature, and by comparing and controlling thedetermined target oil pressure and the current oil pressure to determinethe opening degree of the oil jet valve for cooling the piston.

In addition, the present invention has an effect of reducing thecapacity of the oil pump, which pumps and transfers oil to the maingallery, since the opening degree of the oil jet valve can beselectively varied to correspond to the RPM, the engine load, and theoil temperature by comparing and controlling the target oil pressure andthe current oil pressure.

As is apparent from the above description, the present invention has aneffect of improving performance of a piston and fuel efficiency bydetermining a target oil pressure through a power compensation map, atarget oil pressure curve, and a temperature compensation map, which areset using an RPM, an engine load, and an oil temperature, and bycomparing and controlling the determined target oil pressure and acurrent oil pressure to determine an opening degree of an oil jet valvefor cooling the piston.

In addition, the present invention has an effect of reducing thecapacity of an oil pump, which pumps and transfers oil to a maingallery, since the opening degree of the oil jet valve can beselectively varied to correspond to the RPM, the engine load, and theoil temperature by comparing and controlling the target oil pressure andthe current oil pressure.

The foregoing descriptions of specific exemplary embodiments of thepresent invention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteachings. The exemplary embodiments were chosen and described in orderto explain certain principles of the invention and their practicalapplication, to thereby enable others skilled in the art to make andutilize various exemplary embodiments of the present invention, as wellas various alternatives and modifications thereof. It is intended thatthe scope of the invention be defined by the Claims appended hereto andtheir equivalents.

What is claimed is:
 1. An apparatus for controlling a piston cooling oiljet, comprising: a main gallery supplied with oil; an oil jet gallerydefining an oil injection path, wherein the oil passing through the maingallery is introduced thereinto and is sprayed to a lower portion of apiston; an oil jet valve opening the oil injection path, wherein the oilsupplied to the main gallery is introduced into the oil jet gallery; anda controller electrically connected to the oil jet valve, the controllerdetermining a target oil pressure through a first factor valuecorresponding to an RPM and an engine load, a second factor valuedetermined by a predetermined target oil pressure curve, and a thirdfactor value corresponding to an RPM and an oil temperature in the maingallery, to control an opening degree of the oil jet valve using thetarget oil pressure.
 2. The apparatus of claim 1, wherein the controllerincluding: a power compensation map setting device allowing the firstfactor value to be set; a target oil pressure curve setting deviceallowing the second factor value to be set; a temperature compensationmap setting device allowing the third factor value to be set; and adetermination device configured to determine the target oil pressure byadding a first pressure value, which is obtained by multiplying thefirst and second factor values in a same condition of RPM, to a secondpressure value, which is obtained by a difference between the second andthird factor values.
 3. The apparatus of claim 2, wherein the powercompensation map setting device allows the first factor value to be setfrom an RPM detected by an RPM detection device and an engine load inthe RPM.
 4. The apparatus of claim 2, wherein the target oil pressurecurve setting device allows the second factor value corresponding to anRPM detected by an RPM detection device to be set from the predeterminedtarget oil pressure curve.
 5. The apparatus of claim 2, wherein thetemperature compensation map setting device allows the third factorvalue to be set from an RPM detected by an RPM detection device and theoil temperature in the main gallery measured in the RPM.
 6. Theapparatus of claim 1, wherein the oil jet valve is an electronicsolenoid proportional control valve.
 7. The apparatus of claim 1,wherein the controller is configured to compare the target oil pressurewith a current oil pressure in the main gallery and an oil pressure inthe oil jet gallery through Proportional Integral (PI) control, andcontrols the opening degree of the oil jet valve.
 8. A method ofcontrolling a piston cooling oil jet, comprising: setting a first factorvalue, a second factor value, and a third factor value using an RPM, anengine load, and an oil temperature in a main gallery; and determining afirst pressure value by multiplying the first and second factor valuesin a same condition of RPM, determining a second pressure value by adifference between the second and third factor values in a samecondition of RPM, and determining a target oil pressure by adding thefirst pressure value to the second pressure value.
 9. The method ofclaim 8, further including controlling an opening degree of an oil jetvalve by comparing the target oil pressure with a current oil pressurein the main gallery and an oil pressure in an oil jet gallery.
 10. Themethod of claim 8, wherein, in a setting of a first factor value, asecond factor value, and a third factor value, the first factor value isset from an RPM detected by an RPM detection device and an engine loadin the RPM.
 11. The method of claim 8, wherein, in a setting of a firstfactor value, a second factor value, and a third factor value, thesecond factor value corresponding to an RPM detected by an RPM detectiondevice is set from a predetermined target oil pressure curve.
 12. Themethod of claim 8, wherein, in a setting of a first factor value, asecond factor value, and a third factor value, the third factor value isset from an RPM detected by an RPM detection device and an oiltemperature in the main gallery measured in the RPM.